“And I was like, ‘I haven't ordered anything,’ so I checked it out and saw someone with a different email address had used my account to make those orders,” Prentice, of Hermitage, told Action News’ Paul Van Osdol.

Prentice said he noticed two separate orders on his Best Buy card -- one for a Sony PlayStation and another for iTunes gift cards at $150 each.

But Prentice was only one of many customers victimized by hackers.

Best Buy said a letter to the victims, saying, "These hackers did not take username/password combinations from any Best Buy system; they appear to be using combinations taken elsewhere in an attempt to gain access to BestBuy.com accounts.”

Prentice said Best Buy agreed to waive his charges, but he’s still concerned about making future purchases.

“I'm a little worried about it because I'm a longtime user of Best Buy and I go there a lot, quite often, so I'm a little worried about account security right now,” he said.

Steve Swanson told Van Osdol he recently opened a Best Buy account to buy a computer, but no one warned him of the breach.

“Yeah, I'm concerned about it. It's a lot of money, and I don't need to be paying any more than I am,” he said.

Best Buy officials did not return Van Osdol’s requests for comment.

Security experts encourage users to create a password with more than eight characters, including lowercase and capital letters and at least one numeric or non-alphabetical character.

Using non-dictionary words and changing passwords often can also help increase security.